Neural basis of the effort-reward trade off in rhesus monkeys

Abstract: Decision making crucially relies
upon the arbitrage between costs and benefits. This notion is central in most
disciplines interested in behavior but paradoxically, the neurobiological
substrate of effort remain very unclear compared to that of reward. I will describe a series of experiments in rhesus monkeys (macaca
mulatta) aimed at understanding how the brain adjusts behavioral and
autonomic responses as a function of effort costs and reward benefits. By
combining neurophysiology and pharmacology in a variety of tasks, we showed a
clear functional complementarity between the 2 major catecholaminergic
neuromodulators, dopamine (DA) and noradrenaline (NA). Indeed, the former is
strongly associated with reward whereas the second is strongly associated with effort.
We also examined neural activity in the ventromedial prefrontal cortex (VMPFC),
a key region for subjective evaluation and decision making. Our data indicate
that neurons in this region slowly integrate information about outcome value to
guide actions in a context-dependent manner. Altogether, this work
provides both original insight and questions on the neurobiological constraints
governing the adjustment of behavior as a function of expected costs and
benefits.